Molecular immunology
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Molecular immunology · Jul 2009
Rapamycin enhances LPS induction of tissue factor and tumor necrosis factor-alpha expression in macrophages by reducing IL-10 expression.
Bacterial lipopolysaccharide (LPS) induces monocytes/macrophages to express proinflammatory cytokines and tissue factor (TF), the primary activator of the coagulation cascade. Anti-inflammatory signaling pathways including the phosphatidylinositol-3-kinase (PI3K)-Akt pathway inhibit proinflammatory and TF gene expression in macrophages. We determined the role of Akt, the mammalian target of rapamycin (mTOR) and interleukin-10 in the inhibition of LPS-induced proinflammatory cytokine and TF gene expression in peritoneal macrophages (PMs). ⋯ However, the neutralizing IL-10 antibody did not completely prevent inhibition of LPS-induced TNFalpha and TF expression in PTEN(-/-) PMs. The results indicate that mTOR dependent IL-10 expression leads to inhibition of LPS induction of TF and the proinflammatory cytokine TNFalpha in WT macrophages. In contrast, the decrease in LPS-induced TNFalpha and TF expression in PTEN(-/-) PMs also requires an IL-10-independent pathway.
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Molecular immunology · Jan 2009
Angiotensin-(1-7) enhances angiotensin II induced phosphorylation of ERK1/2 in mouse bone marrow-derived dendritic cells.
It is well known that angiotensin-(1-7) (Ang-(1-7)) counterbalances vasoconstrictive and proliferative functions of angiotensin II (Ang II), some of those actions are via inhibition of Ang II induced activation of mitogen-activated protein kinases(MAPK). This study investigated the effects of Ang-(1-7) on Ang II-mediated cell signaling pathways in mouse bone marrow-derived dendritic cells (DC). The expression of receptor Mas and angiotensin-converting enzyme-related carboxypeptidase (ACE2) mRNA was examined by reverse transcription-polymerase chain reaction (RT-PCR); activation of MAPK was detected by immunoblotting after incubation of dendritic cells with Ang II in the presence or absence of Ang-(1-7), valsartan, PD123319, and D-Ala(7)-Ang-(1-7). ⋯ Both Ang-(1-7) and Ang II had no effect on p38 and c-Jun N-terminal kinase (JNK) phosphorylation. In conclusion, Ang II stimulates ERK1/2 phosphorylation via AT2 receptor in mouse DC, Ang-(1-7) enhances this effect. Generation of Ang-(1-7) by DC could thereby counteract on the pro-inflammatory function of locally generated Ang II.
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Molecular immunology · Nov 2008
Induction of TLR2 expression by inflammatory stimuli is required for endothelial cell responses to lipopeptides.
Human endothelial cells (EC) express Toll-like receptor 4 (TLR4), a receptor for lipopolysaccharides (LPS), but little or no TLR2, a lipopeptide receptor. The aim of this study was to investigate to what extent inflammatory stimuli modify the expression by EC of TLR4 and TLR2, of the TLR2 co-receptors TLR1 and TLR6 and of the TLR2-accessory proteins CD14 and CD36. Stimulation of umbilical vein derived EC with TNF-alpha, LPS or IL-1beta for 24h induced a strong increase in TLR2 mRNA but not in TLR1, TLR4 and TLR6 mRNA. ⋯ This suggests that lipopeptide responses of EC are dependent on the continued presence of inflammatory cytokines, provided by other cell types, or LPS. In conclusion, inflammatory stimuli induce a high TLR2 expression in EC, which in turn enables the cells to strongly respond to lipopeptides. The up-regulation of TLR2 may be of relevance for the vascular effects of Gram-positive bacteria.
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Molecular immunology · Feb 2008
Vaccination of mice with recombinant baculovirus expressing spike or nucleocapsid protein of SARS-like coronavirus generates humoral and cellular immune responses.
Continuous efforts have been made to develop a prophylactic vaccine against severe acute respiratory syndrome coronavirus (SARS-CoV). In this study, two recombinant baculoviruses, vAc-N and vAc-S, were constructed, which contained the mammalian-cell activate promoter element, human elongation factor 1alpha-subunit (EF-1alpha), the human cytomegalovirus (CMV) immediate-early promoter, and the nucleocapsid (N) or spike (S) gene of bat SARS-like CoV (SL-CoV) under the control of the CMV promoter. Mice were subcutaneously and intraperitoneally injected with recombinant baculovirus, and both humoral and cellular immune responses were induced in the vaccinated groups. ⋯ In contrast, there were significantly weaker cellular immune responses, as well as less antibody production than in the control groups. Our data demonstrates that the recombinant baculovirus can serve as an effective vaccine strategy. In addition, because effective SARS vaccines should act to not only prevent the reemergence of SARS-CoV, but also to provide cross-protection against SL-CoV, findings in this study may have implications for developing such cross-protective vaccines.
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Molecular immunology · Jan 2008
IL-17 attenuates the anti-apoptotic effects of GM-CSF in human neutrophils.
Interleukin (IL)-17A is a pleiotropic, pro-inflammatory cytokine that is implicated in chronic inflammatory and degenerative disorders. IL-17 has been demonstrated to link activated T-lymphocyte with the recruitment of neutrophils at sites of inflammation, however whether IL-17 can mediate neutrophil survival and subsequently affect inflammatory responses has not fully been elucidated. In our study, we demonstrate that human peripheral blood and HL-60 differentiated neutrophils express mRNA and cell surface IL-17A receptor. ⋯ These events were associated with reduced myeloid cell lymphoma-1 (Mcl-1) protein levels, increased translocation and aggregation of Bax to mitochondria, decreased mitochondrial transmembrane potential and in an increase in caspase-3/7 activity. These events were independent of increased Fas or soluble Fas ligand expression levels. Taken together, our findings suggest that IL-17 may regulate neutrophil homeostasis and favor the resolution of inflamed tissues by attenuating the delay in neutrophil apoptosis induced by inflammatory cytokines.